Lubricating oil additive



LUBRICATING 01L ADDETIVE Leo V. Mullen, In, Clifton, and James M. Boyle,Bayonne,

N. 3., assignors to Esso Research and Engineering Company, a corporationof Delaware No Drawing. Application January 2, 1952, $erial No. 264,686

19 Claims. on. 252 -475 The present invention relates to lubricating oilcompositions containing as an additive an oxidation inhibiting orcorrosion resisting agent and to the agent itself and method for itspreparation.

In the development of marketable hydrocarbon products such aslubricating oils, the trend has been to use more and more efiicientrefining methods in order to improve their stability and reduce theirtendency to form carbon and deposits of solid matter or sludge. Whilesuch highly refined materials possess many advantages, their resistanceto oxidation, particularly under conditions of severe service, isgenerally decreased and they are more prone to form soluble acidoxidation products which are corrosive. They are generally lessefiective than the untreated products in protecting the metal surfaceswhich they contact against rusting and corrosion due to oxygen andmoisture. Such lubricants also often deposit thick films of varnish onhot metal surfaces, such as the pistons of internal combustion engines.

In accordance with the present invention a new class of chemicalcompounds has been discovered, and these compounds have been found toreduce the tendency of refined lubricating oils and otherhydrocarbonproducts to corrode metal surfaces when added in small quantities tosuch materials. These additives are active in reducing the corrosion ofcopper-lead and cadmium-silver bearings which are employed in internalcombustion engines; they are likewise effective in inhibiting theoxidation of hydrocarbon products generally and especially those ofpetroleum origin; and they impart other useful properties to variousproducts. 1

The new class of compounds forming the subject of the present inventionare formed by sulfur-halogenating an unsaturated ketone containing atleast one olefinic double bond with a sulfur halide. The resultingintermediate compound is then condensed with a salt of a sulfur-bearingacid whereby substantialamounts of halogen are replaced by thesulfur-bearing radical. The resulting compounds are stable and solublein the usual hydrocarbon products such as fuels, lubricating oils andthe like. They are good anti-corrosive agents for organic materials thattend to corrode the usual metals and they have other useful properties.

The ketones, which are sulfur-halogenated by sulfur halides and are thenreduced in halogen content by converting to products containing sulfurbearing radicals, include those having one carbonyl group and containingat least one alkenyl, cycloalkenyl, alkenylaryl, alkenylaralkyl,alkarylalkenyl and the like hydrocarbon radicals. As heretoforementioned, the ketone should contain at least one olefinic double bondcarbon-to-carbon linkage, but the ketone may have two, three, four oreven more such double bonds. It may have conjugated systems of doublebonds; however, 00,13 unsaturated ketones are particularly preferred.Non-acetylenic-types ketones are also preferred. The ketones may have atotal of from 4 to 30 carbon atoms; those having in a range of about 6to 15 are most desirable. Specific unsaturated ketones useful niteclStates Patent in the practice of the present invention, which havealkylalkenyl, dialkenyl, alkylaralkenyl, cycloalkenyl-alkyl and the likeradicals attached to a mono-carbonyl radical, are listed below:

6-methyl-4 hepten-3-one 2,6-methyl-2,5-heptadien-4-one6-methyl-5-hepten-2-one 5-hexen-2-one Z-methyl-hepten- (2) -one-4Diheptadecenyl ketone Cyclohexenylmethylketone 3,5 ,5-trimethylcyclohexen-2-one-1 Benzalacetophenone DibenzalacetoneBenzalacetone Dicinnamylidene acetone Alkyl-alkenyl and dialkenylradicals are generally preferred. The term alkenyl as used herein refersto an aliphatic radical having one or more olefinic double bonds.

For the preparation of the sulfur-halogenated ketones, sulfur halidesselected from the group of sulfur chlorides and sulfur bromides are mostsuitable. Specifically, sulfur dichloride, sulfur monochloride,especially the latter, and sulfur mono-bromide are useful. In the rangeof about 0.2 to 2.0 mol of sulfur halide per mol of ketone may be used.Generally, in the range of at least 0.2 to 1.0 mol of sulfur halide permol of olefinic double bond in the ketone molecule will be employed inorder to introduce sufi'icient sulfur into the molecule to impartcorrosion inhibition properties. The temperature which has been foundmost satisfactory for this reaction is in the range of about 50 to C.,but higher or lower temperatures may be used. The temperature should bemaintained below the decomposition temperature of the halide. Thereaction may be conducted in an inert solvent such as petroleum ether,chloroform, dioxane, ether and the like at refluxing temperature.

The resulting product containing added sulfur and halogen is thenreacted with a salt of a sulfur-bearing acid in order to dehalogenate atleast partially the sulfur-balm genated ketone. The reaction should becarried out with sufiicient salt and under controlled reactionconditions in such a manner that a final product is obtained containingless than about 1.5 weight per cent, preferably below about 1.0 weightper cent, of halogen. Products contain ing greater amounts of halogenare generally excessively corrosive to hearing metals and the like.Conveniently, the amount of salt of the sulfur bearing acid is at leastequivalent, on a. molecular basis, to the halide present in theketone-sulfur halide reaction product. A substantially halogen-freefinal reaction product is then formed.

The sulfur-containing salts of'sulfur-bearing acids may be representedby the general formula GY wherein G is a sulfur-bearing radical havingthe following formulas:

Mercaptide i R 0-iJ-S- Xanthate S R S &-S Thioxanthate N C S RDithiocarb amate RX\fi RX Dieeter of dithtophosphate X in the aboveformulas may be either oxygen or sulfur although oxygen is generallypreferred. R is a hydrocarbon radical having in the range of 1 to aboutcarbon atoms and may be alkyl, alkenyl, cyclo-alkyl, aryl, 'aralkyl andalkaryl radicals. Alkyl radicals such as methyl, ethyl, isopropyl,octyl, dodecyl, lauryl, and the like are preferred. Other hydrocarbonradicals include methyl-cyclohexyl, ethyl cyclo-hexyl, phenyl, naphthyl,benzyl, octylphenyl, and the like. Y is a cation and is preferably ametal equivalent of hydrogen. The reactive alkali and alkaline earthmetals such as sodium, potassium, and calcium, etc., as well as ammoniumor amine salts may be used. The sulfur-containing compounds are preparedby well-known means.

Specific salts of the above general types include potassium, sodium,lithium, barium, ammonium and the like salts of ethyl mercaptan, isoamylmercaptan, allyl mercaptan, n-butyl xanthic acid, hexadecyl xanthicacid, ethylcyclohexyl xanthic acid, n-nonyl thioxanthic acid,benzylthioxanthic acid, isopropyl ethyl dithiocarbamic acid, didodecyldithiocarbamic acid, diethyl dithiocarbamic acid, diphenylethyldithiocarbamic acid, di- (methylcyclohexyl) dithiophosphoric acid,di-(Z-ethylhexyl)dithiophosphoric acid, dicetyldithiophosphoric acid,diLorol-B dithiophosphoric acid (where Lorol-B compounds are derivedfrom Lorol-B alcohol which is a commercial mixture of higher alcoholscommonly derived from coconut oil, and having from 8 to 18 carbon atomsper molecule), di(butyl mercapto) dithiophosphoric acid, and the like.Mercaptide and dithiocarbamate derivatives are particularly preferred inthe present invention.

The various sulfur-bearing acid salts are not necessarily equivalent,and the type of derivative to be produced will depend largely on theconcentrations used and the specific properties to be improved invarious hydrocarbon products. For a given carbon content, mercaptidederivatives usually have an advantage from the standpoint of oilsolubility and compatibility combined with good corrosion inhibitionproperties. Thiocarbamate derivatives, in addition to having goodantioxidant and corrosion inhibition properties, will frequently bepreferred as additives for minimizing ring sticking in motors. Thedithiophosphate derivatives will sometimes be especially valuable forimparting mild extreme pressure properties to gear oils and the like.Thioxanthate and dithioester dithiophosphate derivatives will frequentlybe used in cutting oils where high sulfur concentrations are desired.

In carrying out the reaction, the sulfur-containing salt may be addedrelatively slowly to the sulfur-halogenated ketone with care being takento prevent excessive temperature rise as a result of the exothermicreaction which takes place. The reactants may be heated together for aperiod of from about 0.5 to 2 hours, depending on the types of materialspresent. Preferably, the reaction temperatures are maintained in a rangeof about 50 to 150 C. Conveniently, the reaction is carried out in thepresence of an inert solvent in which the halide reaction by-productsare insoluble or from which such by-products may be readily removed.Such solvents include petroleum ether, methyl alcohol, ethyl alcohol,isopropyl alcohol, acetone, dioxane and the like. The heating step maybe carried out under refluxing conditions when a solvent is used. Theresulting metal halide will generally precipitate out of solution andmay be removed by filtration, decantation or by other means. Solvent maybe removed from the finished product by stripping with nitrogen or otherinert gas, by distillation or by other means. A desired method forproducing a relatively pure product is to filter the materials,preferably before solvent is removed, through a diatornaceous filter aidsuch as Hy fl If the products of the present invention are added to amineral oil for inhibiting oxidation and preventing corrosion of metalparts and the like, they are preferably 4 used in proportions of about0.01 to 5% or 10% by weight based on the total composition. A preferredrange is from about 0.1 to 2% by weight. Concentrations up to as high as20% or even higher may be used for extreme pressure lubricants, cuttingoils, and the like or for concentrates. It is usually preferred, whenmarketing the additive commercially and especially when intended for usein lubricating oils, to prepare a concentrated lubricating oil solutionin which the amount of additive in the composition ranges from about 20to 50% or higher by weight, depending on the solubility of the additivein the oil. The concentrate is then conveniently transported and storedin such form and may be subsequently blended with a base lubricant inthe required amount before it is used as a crank case oil or the like.

The invention will be more fully understood by reference to thefollowing examples. It is pointed out, however, that the examples aregiven for the purpose of illustration only and are not to be construedas limiting the scope of the present invention in any way.

Example I Per cent Sulfur 42.43 Chlorine 3.71

(b) 24 grams (0.1 mols) of di-N-octylamine were added dropwise withstirring to 4 grams of NaOH (0.1 mol) dissolved in cc. of methyl ethylketone. To this reaction solution were added with external cooling 7.6grams (0.1 mol) of CS2 dissolved in 25 grams of methyl ethyl ketone.

(c) 100 grams of the S2Cl2 treated ethyl amylene ketone (prepared inPart a) were added dropwise to the sodium di-N-octyl thiocarbamatesolution (prepared in Part 12 and equivalent to 3 mols per mol ofchloride in sulfurchlorinated ketone). The resulting solution wasrefluxed for two hours and then filtered. The MEK was distilled off,leaving a product having the final analysis:

Per cent Sulfur 29.36 Chlorine 0.92 Nitrogen 1.31

Example II Sulfur, wt. per cent 30.97 Chlorine, wt. per cent 8.79

(b) 12 grams of NaOH (0.3 mol) and 60 grams (0.3 mol) of laurylmercaptan were added to 108 grams of the S2Cl2 treated phorone (preparedin Part a) dissolved in cc. of methyl ethyl ketone (equivalent to 1.1mol mercaptan/mol of chloride in sulfur-chlorinated phorone). Theresultant reaction mixture was refluxed for two hours with vigorousstirring and then filtered. The MEK ,5 was distilled off, leaving aanalysis:

product having the final Example IIl.Lauson engine test The productsprepared as described in Example I were tested in a Lauson engine, usinga blend of 1% by weight of the additive in a solvent extractednaphthenic oil of SAE 30 grade. For comparison, a sample of theunblended base oil was likewise tested. The test was conducted for aperiod of 25 hours, the Lauson engine being operated at 1800 R. P. M.with a 1.5 indicated kilowatt load, 300 F. oil temperature and 295 F.water jacket temperature. The oils were rated on a demerit systemwherein an oil giving a perfectly clean piston surface is given a ratingof 0, while a rating of is given to an oil giving the worst conditionwhich could be expected on that surface. Observations were also made onthe loss in weight of the copper-lead bearing during each test. Theresults are shown in the following table:

Example IV.--Lab0ratory bearing corrosion test A blend was preparedcontaining 0.25% by weight of each of the additives prepared asdescribed in Examples 1(c) and 2(b), using as the base oil an extractedMid Continent paratfinic lubricating oil of SAE grade. Samples of theseblends and a sample of the unblended base oil were submitted to alaboratory test designed to measure the effectiveness of the additive ininhibiting the corrosiveness of a typical mineral lubricating oiltowards the surfaces of copper-lead bearings. The test was conducted asfollows:

500 cc. of the oil was placed in a glass oxidation tube (13 inches longand 2% inches in diameter) fitted at the bottom with a A inch air inlettube perforated to facilitate air distribution. The oxidation tube wasthen immersed in a heating bath so that the oil temperature wasmaintained at 325 F. during the test. Two quarter sections of automotivebearings of copper-lead alloy of known weight having a total area of sq.cm. were attached to opposite sides of a stainless steel rod which wasthen immersed in the test oil and rotated at 600 R. P. M. thus providingsufiicient agitation of the sample during the test. Air was then blownthrough the oil at the rate of 2 cu. ft. per Hour. At the end of eachfourhour period the bearings were removed, washed with naphtha andweighed to determine the amount of loss by corrosion. The hearings werethen repolished (to increase the severity of the test), reweighed, andthen subjected to the test for additional four-hour periods in likemanner. The results are given in the following table as corrosion life,which indicates the number of hours required for the hearings to lose100 mg. in weight, determined by interpolation of the data obtained inthe various periods.

Bearing Corrosion Life (Hrs.)

Oil

Unblended base oil Base oil +0.25% product of Example 1(0) Base oil+0.25% product of Example 2(b) The additives of the present inventionmay be used in various lubricating oil base stocks derived frompetroleum distillates and residuals refined by conventional means.Hydrogenated oils or white oils may be employed as well as syntheticoils prepared by polymerization of olefins, by reaction of oxides ofcarbon with hydrogen, or by hydrogenation of coal. The products may alsobe used in the synthetic poly-ether and poly-ester-type lubricants andthe like as such or blended with mineral base lubricants. The lubricantswill usually range from about 35 to 150 seconds (Saybolt) viscosity at210 F.

Other agents may of course be employed in the oil compositions, suchagents including dyes, pour point depressants, sludge dispersers,thickeners, viscosity index improvers, oiliness agents, and the like. Inaddition to being employed in lubricants, the additives of the presentinvention may also be used in other mineral oil products such as motorfuels, heating oils, hydraulic fluids, cutting oils, turbine oils,transformer oils, gear lubricants, greases and other products containingmineral oils as ingredients.

What is claimed is:

l. A composition comprising a major proportion of a petroleumhydrocarbon product and a minor oxidation inhibiting quantity of productobtained by reacting a mono-carbonyl ketone containing at least oneolefinic double bond, and having in the range of 4 to 30 carbon atoms,with a sulfur halide selected from the class consisting of sulfurchlorides and sulfur bromides, whereby an intermediate productcontaining added sulfur and halogen is formed, further reacting suchintermediate product with a sulfur bearing compound of the formula GYwherein G is a radical selected from the group consisting of SR,

and

Y is a cation selected from the group consisting of alkali metals,alkaline earth metals and ammonium radicals, R is a hydrocarbon radicalhaving in the range of l to about 20 carbon atoms, and Z is selectedfrom the class consisting of oxygen and sulfur, by heating together at atemperature in the range of about 50 to 150 C. for a period of timesufficient to produce a final reaction product which, after separationof by-product cation halide, contains not more than about 1.5% by Weightof halogen.

2. A composition as in claim 1 in which said petroleum hydrocarbonproduct is a lubricating oil fraction.

3. A composition as in claim 1 in which said ketone has in the range of6 to 15 carbon atoms and said sulfur halide is sulfur monochloride.

4. A composition as in claim 3 in which said ketone is an alkyl alkenylketone.

5. A composition as in claim 3 in which said ketone is a dialkenylketone.

6. A composition as in claim 3 in which said sulfur bearing compound isa metal dialkyl dithiocarbamate in which each alkyl radical has in therange of l to 20 carbon atoms.

7. A composition as in claim 3 in which said sulfur bearing compound isan alkyl mercaptide having in the range of l to 20 carbon atoms.

8. A composition consisting essentially of a mineral lubricating oil andthe reaction product as defined in claim 1, the amount of said reactionproduct in the composition being in the range of about 20 to 50% byweight.

9. The process which comprises the steps of reacting a mono-carbonylketone containing at least one olefinic double bond and having in therange of 4 to 30 carbon atoms with a sulfur halide selected from theclasses consisting of sulfur chlorides and sulfur bromides whereby anintermediate product containing added sulfur and halogen is formed,further reacting such intermediate product 'with a sulfur bearingcompound of the formula GY wherein G is a radical sele'ctedfrom thegroup consisting of SR,

Y is a cation selected from the group consisting of alkali metals,alkaline earth metals and ammonium radicals, R is a hydrocarbonradicalhaving in the-range of 1 to about 20 carbon atoms, and Z is selectedfrom the class consisting of oxygen and sulfur, by heating together at atemperature in the range of about 50 to 150 C. for a period of timesuificient to produce a final reaction product which, after removal ofby-product cation halide, contains not more than about 1.5% by weight ofhalogen.

10. A process as in claim 9 wherein said ketone has in the range of '6to 15 carbon atoms and said sulfur halide is sulfur monochloride,

11. A process as in claim 10 wherein said ketone is ethyl amyleneketone.

12. A process as in claim 10 wherein said ketone is phorone.

13. A process as in claim 10 wherein said sulfur hearing compound is ametal dialkyl dithiocarbamate in which 8 each alkyl radical has in the"range of 1 to 20 carbon atoms.

14. A process as in claim 10 wherein said sulfur bearingcom'po'und isanalkyl mercaptide having in the range of 1 to 20 carbon atoms.

15. A process as in claim 9 wherein Yis a metal and the reaction isconducted in a medium in which the byproduct metal halide is insoluble.

16. As a new composition of matter, the product of claim 9.

17. As a new composition of matter, the product of claim 10.

18. As a new'composition of matter, the product of claim 13.

19. As a new composition of matter, the product of claim 14.

References Cited in the file of this patent UNITED STATES PATENTS2,179,062 Smith et a1 Nov. 7, 1939 2,217,764 Morway et al Oct. 15, 19402,242,260 Prutton May 20, 1941 2,305,401 Armendt Dec. 15, 1942 2,313,611Abramowitz et al Mar. 9, 1943 2,405,482 Zimmer et al. Aug. 6, 19462,451,346 McNab et al Oct. 12, 1948 2,516,119 Hersh July 25, 1950

1. A COMPOSITION COMPRISING A MAJOR PROPORTION OF A PETROLEUMHYDROCARBON PRODUCT AND A MINOR OXIDATION INHIBITING QUANTITY OF PRODUCTOBTAINED BY REACTING A MONO-CARBONYL KETONE CONTAINING AT LEAST ONEOLEFINIC DOUBLE BOND, AND HAVING IN THE RANGE OF 4 TO 30 CARBON ATOMS,WITH A SULFUR HALIDE SELECTED FROM THE CLASS CONSISTING OF SULFURCHLORIDES AND SULFUR BROMIDES, WHEREBY AN INTERMEDIATE PRODUCTCONTAINING ADDED SULFUR AND HALOGEN IS FORMED, FURTHER REACTING SUCHINTERMEDIATE PRODUCT WITH A SULFUR BEARING COMPOUND OF THE FORMULA GYWHEREIN G IS A RADICAL SELECTED FROM THE GROUP CONSISTING OF-SR,